Fingerprinting continues to be the principle means by which police agencies identify criminals and solve crimes. The characteristic ridge patterns (minutiae) upon the palmar surfaces of hands and feet, especially upon finger tips, differentiate one human being from another, since generally speaking no two people have the exact same minutiae/ridge patterns.
Impressions of these unique ridge patterns are inevitably left behind when a person touches a surface with their finger, since natural secretions (e.g. sweat, natural oils, etc.) residing on the friction ridges of the finger will deposit fingerprint residues in a characteristic ridge pattern upon the surface. Police agencies can capitalise upon these deposits (latent fingerprints), and the uniqueness of each characteristic pattern, by “dusting for fingerprints” at a crime scene. This typically involves applying a ‘developer’ (e.g. with a fingerprint brush), typically a fingerprint powder, to a surface comprising or suspected of comprising a latent fingerprint, in order to enhance the contrast between the ridge pattern left by the fingerprint residues and the surface itself. Usually, once the ‘developer’ has been applied to the surface any excess powder is blown away to leave an imagable fingerprint impression pattern (corresponding to the minutiae of the latent fingerprint) which can either be directly imaged (e.g. through the taking of a photograph) and/or tape-lifted (i.e. by extracting the imagable fingerprint impression pattern from the surface with adhesive tape so that the pattern then resides on the adhesive of the tape) for later use/analysis. The imaged fingerprint can then be either compared to fingerprints in a fingerprint database and/or kept on record to facilitate identification of criminals or other persons who may have touched the surface which has been “dusted for fingerprints”.
Currently a wide variety of fingerprint powders (developers) are available for use in fingerprinting. For instance, haddonite white, which is ideal when dusting for fingerprints on dark surfaces, contains titanium dioxide, kaolin, and French chalk, whilst dactyl black, which is more suitably for light surfaces, contains a combination of graphite, lampblack, and gum acacia.
Often a particular fingerprint powder will be chosen to complement the surface in question. For instance, a dark coloured fingerprint powder is often employed for developing fingerprint patterns upon a light surface, and vice versa. An inherent problem exists in that different fingerprint powders must be used for different background surfaces in order to achieve optimal contrast between the fingerprint pattern and the background, since each individual fingerprint powder is generally tailored to complement certain qualities of the background. This requires a forensic investigator to be either equipped with multiple different types of fingerprint powders, which is highly inconvenient and fingerprinting opportunities may be scuppered if the forensic investigator “dusts” with the wrong type of fingerprint powder, or to compromise on image quality.
It is thus an object of the invention to solve one of the problems inherent with the prior art.
Another object of the invention is to provide a single fingerprint powder which may be appropriate for use on a variety of (radically) different background surfaces.